Acoustically stealthy soft-bodied uuv propulsion system

Abstract

An acoustically stealthy, soft-bodied underwater propulsion system includes a central chord member and a series of successive muscle layers each having a skeletal mechanism and a set of actuators. Each skeletal mechanism includes a central vertebra, two or more actuator arms extending radially outward from the central vertebra and disposed axially symmetrically about the central chord member, and an actuator plate extending from a radially outward end of each actuator arm and oriented substantially transverse to the actuator arm. Each actuator is situated between an actuator plate from a first muscle layer of the series and a second muscle layer of the series.

Description

RELATED APPLICATIONS[0001]This application claims the benefit of U.S. Provisional Application No. 62 / 597,675 filed Dec. 12, 2017, which is hereby incorporated herein by reference.FIELD OF INVENTION[0002]The present invention relates generally to underwater vehicles, and more particularly to biomimetic underwater vehicles.BACKGROUND[0003]Soft robotics and electro-active polymers are emerging fields that could revolutionize autonomous undersea platforms. Cutting-edge Unmanned Underwater Vehicle (UUV) speed, range, and stealth are limited by:[0004]1. Noisy and inefficient propulsion mechanisms such as propellers and rotating machinery that produce more easily detected ‘tonal’ noise.[0005]2. Suboptimal hydrodynamics and propulsion modes that limit the speed at which acoustic measurements can be taken, in addition to limiting endurance and consequently survey area.[0006]3. Structural impedance mismatch due to the use of syntactic foam and hollow pressure vessels that efficiently reflect ...

AI Technical Summary

Benefits of technology

[0011]A soft robotics approach using elastic, electro-active polymers and flexible, tough thin-film batteries may replicate the high efficiencies seen in nature through complete mimicry of form and function, while increasing the ability of the UUV to withstand collisions and environmental damage. Soft robots are built using a modern variety of polymers, nanostructures, and other materials that deform reversibly when electrical current, differing temperatures, or other external energy is applied. These materials can be arranged to work in a manner similar to biological muscle: high-force linear contraction and relaxation, as opposed to rotational movement. Such actuation mechanisms possess tremendous potential for application in silent or near-silent propulsion systems because no rigid bearings or sliding rigid members may be required in their design.

[0013]In addition to improving speed and range, noise from thunniform movement is limited to broadband flow noise, which largely decays in an evanescent manner with distance from the source. In addition, these low-cost organic polymers may be tuned to match the impedance of water, creating an acoustically transparent propulsion system.

[0014]Therefore, presented herein is an unprecedented UUV that achieves high-speed endurance and simultaneously low self-noise for use as an acoustic sensing platform. Exemplary soft-bodied, truly biomimetic (both in a hydrodynamic and structural / energy recovery sense) autonomous vehicles replicate the cruise speeds, noise levels, stealth, and energy efficiencies of solitary, highly migratory pelagic organisms. Exemplary platforms travel quickly with low self-noise, while offering enhanced resistance to collision damage; goals that are difficult to achieve with conventional UUV designs.

Problems solved by technology

However, very little work has been performed on replicating the structural efficiencies of internal propulsive structures (musculature) or energy recovery systems (elastic ligaments) employed by pelagic fishes, let alone the integration of these components into a fully functional system.

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